Cartridge

ABSTRACT

A cased cartridge for firearms in which the cartridge casing is expelled through the muzzle along with the projectile or projectiles to provide the advantages of caseless ammunition in a cased round.

United States Patent 1 1 3,728,966

Woodring 51 Apr. 24, 1973 [541 CARTRIDGE 3.288.066 11/1966 Stadleret a1. ..102/3s 3,336.87i 8/1967 Quinlan ..102/38 [75] Inventor" woodr'ng Stone) 3.363562 1/1968 Stadleret a1. ..I02/43 Creek, Conn. 3.399.622 9/1968 Houdek 102 42 C [73] Assignaez 1 n E c rc 3.422.761 1/1969 Whitmore ..102/42 C tron, New Haven, Conn. FOREIGN PATENTS OR APPLICATIONS 1 1 Filedl May 7, 1963 1,449,850 7/1966 France ..1o2 42 1 pp No 727,164 732,633 6/1955 Great Britain ..102/43 Primary Examiner-R0bert F. Stahl [52] U-S- C -10 C, 0 /38. 0 3 Attorney-Donald R. Motsko, H. Samuel Kieser, Wil- 0 5 liam W. Jones, Richard S. Strickler, Robert H. [5 l Int. Cl ..F42b 7/06 Bachman and Thomas P. ODay [58] Field of Search ..102/38,42, 43,42 C,

102/43 C, 95, 43 P, 44, DIG. 1, DIG. 5; 89/1 [57] ABSTRACT A cased cartridge for firearms in which the cartridge [56] References Clted casing is expelled through the muzzle along with the UNITED STATES'PATENTS projectile or projectiles to provide the advantages of caseless ammunition in a cased round. 3,352,239 11/1967 Schinnererm; ..102/43 C 3,577,921 5/1971 Van Langenhoven ..102/38 15 Claims, 5 Drawing Figures 3,048,849 8/1962 De Caro .102/38 X 1,191,357 7/1916 Snyder... ..89/1 3,097,169 7/1963 Hall ....102/38 X PATENIED APR 24 I973 INVENTOR. WILL /AM 8. wooo/m/c ATTORNEY CARTRIDGE This invention relates to ammunition and more particularly to shotshell type ammunition in which the entire round of ammunition including the casing, wads, projectiles, etc., is expelled through the muzzle of the firearm upon firing. A round of ammuntion made in accordance with this invention eliminates the necessity of ejecting and extracting a spent case as is required with conventional shotshell type ammunition.

A conventional shotshell includes a tubular case formed from plastic or paper, a metallic head formed on one end of the casing and a closure formed at the opposite end, usually by infolding an end portion of the casing. The internal components comprise a charge of powder, one or more wad elements and a shot charge. A primer positioned in the head of the case ignites the propellant, which in turn fires the wadding and the shot charge down the barrel of a firearm. The empty fired case, retained in the chamber, is then extracted and ejected from the chamber and an unfired round is then loaded into the chamber for firing.

The present invention contemplates an entirely new ammunition concept wherein the casing, as well as all the other components of a shotshell, are expelled through the muzzle of a firearm when the cartridge is fired. This eliminates the necessity of ejecting and extracting the shotshell, thereby simplifying the function and number of component parts required in the firearm.

The ammunition of this invention combines the advantages of caseless ammunition systems, in which the entire cartridge is consumed upon firing, with many of the advantages of conventional cased ammuntion. Ammunition of this invention is relatively durable and may be handled in substantially the same manner as a conventional cased shotshell. There is no fired casing remaining in the chamber after the ammunition of this invention is fired, thus the need to extract and eject a fired casing is obviated.

A major advantage attendant to the ammunition of this invention lies in the economic area. The ammunition of this invention can be produced at substantially lower cost than conventional cased shotshells. A factor contributing to the lower cost of the ammunition of this invention is the elimination therefrom of a metallic head portion found in conventional shotshells. Furthermore, the expendable casing of this invention can be economically manufactured by conventional means, such as injection molding of plastic. Special materials and processes to strengthen the casing by cold working and bi-axial orientation are not required for the casing of this invention, while they are so required for conventional plastic shotshells. Thus it is contemplated that ammunition having superior quality can be offered to the average shooter at a substantially reduced cost.

It is, therefore, an object of this invention to provide a new type of ammunition which is economical to manufacture, is durable and can be readily handled and packaged, and has superior performance.

It is a further object of this invention to provide a cased shotshell for a firearm in which the entire shotshell, including the casing, is expelled through the muzzle upon firing, thereby eliminating the need for extracting and ejecting a spent cartridge casing.

It is yet another object of this invention to provide a new type of ammunition having a molded plastic casing which can be economically manufactured in conventional machinery by known processes.

These and other objects of this invention will be more fully disclosed in detail below with reference to the attached drawings in which:

FIG. 1 is a side view partially in section of a shotshell formed in accordance with this invention;

FIG. 2 is a side view partially in section of a modified embodiment of the shotshell of FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 0s a side view partially in section of a second is embodiment of a shotshell formed in accordance with this invention; and

FIG. 5 is a side sectional view of a portion of a firearm showing the shotshell of FIG. 4 seated in the firing chamber, and showing the engagement between the bolt and the shotshell.

Referring now to FIG. 1, a preferred embodiment of this invention is shown in the form of a shotshell. The shotshell includes a cylindrical casing, denoted generally by the numeral 2, formed preferably of injection molded polyethylene, or other flexible plastic material. The casing 2 is subdivided by an internal transverse web 4 into a forward facing cup portion 6 and a rearward facing cup portion 8. While the cup portions 6 and 8 are preferably formed as integral members, it is to be understood that the cups 6 and 8 can be formed as separate members which are subsequently joined together without departing from the spirit of this invention. The forward cup portion 6 serves to receive a pair of wads 10 disposed adjacent to the web 4 and a charge of shot pellets 12 adjacent to the wads 10. While a pair of wads 10 are shown in the forward cup 6, it is understood that the exact number of wads in the cartridge may be varied without departing from the spirit of this invention. Furthermore, the wads 10 may be entirely omitted from the forward cup 6 and may be compensated for by merely increasing the thickness of the transverse web 4 to provide additional cushioning for the shot charge. The forwardmost end of the cup portion 6 is closed by means of a cup 14 which overlies the shot charge 12. The cup 14 is preferably formed from polystyrene, polyethylene, paper, or some other relatively lightweight material. The cup 14 is retained in place over the shot charge 12 by means of a cone crimp 16 formed at the upper edge of the cup portion 6, which cone crimp l6 slightly overlaps the edges of the cup 14. While a cup and an associated cone crimp are preferred for forming the closure of the shot containing cup 6, a disk of either frangible or nonfrangible material may be used in place of the cup 14. Furthermore, it is contemplated that an integral closure in the form of a folded over crimp may be used to close the top of the forward cup 6.

The rearward cup portion 8 is operative to receive a compacted propellant pellet 18. The propellant pellet 18 may be adhesively secured to the inner wall of the cup portion 8, or it may be frictionally press fitted therein or retained by other suitable means. The propellant pellet 18 shown is of the impact ignition variety and includes a charge of primer material 20 deposited in a recess 22 in the rear face of the pellet l8.

While the pellet shown is of the impact ignition type, it is understood that propellant pellets ignitable by other known means may be utilized without departing for the spirit of this invention. The propellant pellet 18 is preferably formed from a compressed mass of slightly fibrous explosive, such as virgin nitrocellulose, or other compactible powder. The pellet may be formed by either wet or dry compaction methods. The rearward cup portion 8 preferably includes a skirt 24 operable to seal combustion gases after the cartridge has been fired and the inner surface of which provides for frictional engagement with the outer surface of a bolt assembly when chambered in a firearm. It is noted that the outside diameter of the forwardly facing cup portion 6 is smaller than the outside diameter of the rearwardly facing cup portion 8 with an oblique shoulder 26 being formed on the exterior of the casing 2 intermediate the outside surfaces of the respective cup portions 6 and 8. The shoulder 26 serves to seat the cartridge in a firing chamber of a shotgun and provides a surface on the cartridge operable to generate shot start after the propellant has been ignited.

The cartridge formed in accordance with this invention is preferably used with a full choke shotgun and operates in the following manner. The cartridge is inserted into the firing chamber of a firearm with the shoulder 26 being seated against a complimentary shoulder or seat formed in the firing chamber. The bolt is then brought to the battery position and into frictional engagement with the inner surface of the skirt 24, and the propellant charge 18 is ignited. Initially after ignition of the propellant, the shoulder 26 bearing against the firing chamber seat resists forward movement of the cartridge until a predetermined gas pressure is reached. The resistance of the shoulder 26 is overcome and the entire cartridge, including the casing 2 is propelled through the barrel of the firearm. As the cartridge passes through the firearm barrel, the skirt 24 flexes outwardly to seal combustion gases, and the wall of the forward cup portion 6 prevents contact between the shot pellets l2 and the bore wall of the barrel. When the cartridge reaches the choke, the casing 2 is slowed by engagement therewith while the shot charge 12 passes out through the front end of the forward cup 6 dislodging the cup 14 and deforming the cone crimp 16. The casing 2 continues through the choke and is expelled from the muzzle of the gun.

Referring now to FIGS. 2 and 3, a modified embodiment of the cartridge of FIG. 1 is shown. The modified cartridge includes a casing 2 having a forwardly facing cup portion 6' and a rearwardly facing cup portion 8. The casing 2' is structurally identical to the casing 2, with the exception that the exterior surface ofthe rearward cup portion 8' includes a plurality of undercut areas, such as at 28, which are circumferentially spaced apart to define intermediate lugs 30 which extend forwardly from the front end of the outer surface of the cup 8. The lugs 30 include forward oblique faces defining shoulders 32 which are operative to engage a complimentary shoulder or seat in the shotgun firing chamber. A comparison between the shoulder 26 on the casing 2, and the shoulders 32 on the casing 2' shows the latter to be of lesser total area, thereby providing less resistance to movement of the cartridge past the firing chamber seat after firing. Thus the cartridge embodiment shown in FIG. 2 will fire at a lower shot start value than the cartridge shown in FIG. 1. It is to be understood that while FIGS. 2 and 3 disclose three equal area lugs 32 equally spaced about the circumference of the cartridge casing 2, the size and spacing of the lugs may be varied to vary shot start without departing from the spirit of this invention.

Another modification of a cartridge formed in accordance with this invention is shown in FIG. 4. The cartridge of FIG. 4 includes a casing 2" having a forwardly opening cup portion 6" and a rearwardly opening cup portion 8". A transverse web portion 4 is interposed between the cups 6" and 8". A wad 10" and a shot charge 12" are disposed in the forward cup portion 6", with a disk member 15 serving to close the mouth of the forward cup portion 6". The disk 15 is retained in place by a cone crimp 16" formed at the upper edge of the cup wall. The rearwardly opening cup portion 8" includes a first flexible inwardly extending annular lip 34 formed on the inner surface of the cup 8" intermediate the ends thereof. A propellant pellet 18" is disposed in the cup 8" with the lip 34 overlapping the edge of the pellet 18" to retain the latter in the cup 8". It is readily apparent that the lip 34 must be sufficiently flexible to permit the pellet 18" to be inserted into the cup 8" without damaging the former, while at the same time being sufficiently rigid to retain the pellet 18" in the cup 8". A second inwardly extending lip 36 is formed at the rim of the cup 8" to provide means for engaging the bolt on a firearm, which means provides for a more positive engagement between the bolt and cartridge than does the previously noted frictional engagement between the bolt and the inner surface of the skirt, as will be set forth in more detail hereinafter. An oblique shoulder 26" is interposed between the outside surfaces of the forward cup 6" and the rearward cup 8". A generally forwardly extending flexible flange 38 is formed at the rearward edge of the shoulder 26" where the latter intersects the outer surface of the rearward cup 8". The flange 38 preferably extends around the entire periphery of the cup 8".

FIG. 5 shows the cartridge of FIG. 4 seated in a firearm and ready to be fired, and further shows the function of the lip 36 and flange 38. The shotgun, shown only fragmentarily, includes a barrel bore 40 and a bolt housing 42 which are open one to the other. An inwardly extending annular protrusion 44 is interposed between the bolt housing 42 and the barrel bore 40, to define a firing chamber area, the protrusion 44 including an oblique face 46 providing a complimentary seat for the shoulders 26 or 32, or for the flange 38 on the various embodiments of the cartridge of this invention. A bolt assembly 48 is disposed in the housing 42 and is shown in the battery position. The bolt assembly 48 includes a head portion 50 of reduced diameter which telescopes into the open end of the cup 8" on the cartridge. A groove 52 is formed on the outside surface of the bolt head 50, the groove 52 providing a recess into which the cartridge lip 36 is received as the head 50 moves into the cartridge cup 8". The lip 36 and groove 52 provide a positive connection between the bolt assembly 48 and the cartridge casing 2" whereby the latter may be extracted from the firing position should one desire to unload a loaded gun, or

should a misfire occur. It is noted that the lip 36 must be sufficiently flexible to release from the groove 52 when the cartridge is fired, but sufficiently rigid to remain in the groove 52 when the bolt assembly 48 is moved to its retired position should the cartridge not be fired.

As shown in FIG. 5, when the cartridge is placed in its firing position and the bolt assembly 48 is moved to its battery position, the flange 38 is moved against the seat 46 in the firing chamber. By providing a flexible flange 38 which can be deflected or crushed against the seat 46 as the bolt assembly 48 moves to its battery position, the propellant pellet 18" is protected against excessive and possibly damaging pressure which could otherwise be directed against it by the front face of the bolt assembly 48. Thus the flange 38 provides a flexible shoulder for seating in the firing chamber, rather than a rigid one.

When the firing pin 54 is caused to strike the primer 20", the propellant 18" is ignited producing high pressure gases. The gases are sealed by gas grooves 56 formed in the bolt assembly, and when the gas pressure reaches a predetermined level, shot start is initiated, the rearward cup 8" is driven past the protrusion 44, and the entire cartridge is driven through the barrel bore 40.

it is thus readily apparent that this invention provides cased ammunition which, when tired from a firearm, leaves no casing in the firearm to be extracted and ejected. Furthermore, shotshell ammunition of substantially reduced cost can be produced in accordance with this invention while sacrificing substantially none of the durability and quality of conventional shotshells.

What is claimed is:

l. A cartridge casing of deformable plastic material which is completely expelled from the muzzle of a firearm when fired, said casing comprising: a tubular plastic body; a transverse web fixed to the interior of said body intermediate the ends thereof to divide said body into forward and rearward portions; and shoulder means formed on the exterior surface of said body to provide shot start resistance to said casing when chambered in a firearm, said shoulder means comprising circumferentially spaced shoulders separated from each other by undercut portions.

2. A cartridge including an open ended tubular plastic casing, said casing having a forward portion of reduced diameter and a rearward portion of enlarged diameter, a shoulder between said forward and rearward portions, a transverse web positioned within said casing and forminga common wall between said forward and said rearward portions, wad means positioned within said forward portion, projectile means positionedwithin said forward portion, closure means closing an end of said forward portion, and propellant means positioned within said rearward portion of said casing.

3. A firing system in which the entire cartridge is expelled from the muzzle ofa firearm, said cartridge comprising a cartridge case and an associated projectile means, said cartridge case being made of deformable, plastic material and comprising an elongated, generally tubular member having a mouth end and a breech end at the opposite end thereof, transverse wall means integrally formed intermediate said ends to form with said elongated member an open-ended propellant cavity at the breech end and an open-ended projectile cavity at the mouth end, projectile means positioned and secured in said projectile cavity, said propellant cavity having its open end closed off by a molded, consumable propellant means which is substantially entirely consumed upon firing, consumable ignition means positioned and secured in said propellant means, said firearm from which said cartridge is to be expelled after firing comprising a gun barrel having a bore of lesser diameter than said cartridge case and a gun chamber in which said cartridge is positioned for firing, means abutting said cartridge to limit forward movement of the cartridge into the chamber prior to firing and to give support thereto during firing, said cartridge case adapted to be deformed so as to be entirely expelled through the smaller bore diameter of the gun barrel upon firing without leaving any portion thereof in the gun.

4. An expendable cartridge comprising a case made of deformable plastic material which is not combustible under normal firing conditions, a transverse wall means integrally formed with said case to define an openended projectile chamber at its mouth end and an open-ended propellant chamber at its breech end, said cartridge case being of maximum diameter adjoining said propellant chamber and of minimum diameter adjoining said projectile chamber, projectile means at least partially positioned in said projectile chamber and secured therein, propellant means, at least a portion of which is of solid unitary construction, positioned in said propellant chamber so that said solid propellant portion closes off the open end of said propellant chamber, priming means positioned in and secured to said solid propellant portion, said propellant means and said priming means being entirely made of consumable materials so that upon firing said propellant means and said priming means are substantially entirely consumed whereupon said plastic cartridge case is deformed and forced out of the gun barrel behind the projectile means thus resulting in the entire cartridge being expelled from the gun.

5. A shotshell which is expelled from the gun upon firing comprising an expendable body having a rear chamber open at its rear end thereof, propellant means and priming means positioned and secured in said rear chamber, a forward chamber open at its front end and having a shot charge positioned therein, imperforate wall means separating said forward and rear chambers to prevent explosive gases formed in the rear chamber from entering said forward chamber, a shoulder means formed integrally with said body on the outer surface thereof between the open ends thereof, and closure means closing off the open end of said front chamber to confine the shot charge in the front chamber during handling but adapted to release the shot charge after the expendable body and shot charge are explosively expelled from the muzzle of the gun.

6. An expendable shotshell cartridge comprising a thermoplastic body member having a first chamber open at one end, propellant means and priming means positioned and secured within said first chamber, a

second chamber at the opposite end of said body chambers being separated from each other by an imperforate wall means which remains attached to the body member after firing, a continuous rim means formed integrally with the body at the open end of said first chamber to act as a seal and to provide support to hold the shell in a gun chamber, said rim means being adapted to hinge inwardly under pressure upon firing of the cartridge and to remain attached to the body while the entire cartridge and shot charge therein is expelled from the muzzle of the gun.

7. An expendable cartridge adapted to be expelled from the barrel of a gun, said expendable cartridge comprising a body member made of thermoplastic material, a transverse, imperforate wall means formed with said body member to define therewith a propellant chamber at the rear thereof and a projectile chamber at the front thereof, projectile means positioned in said projectile chamber, propellant means and priming means positioned in said propellant chamber, transverse closure means retaining said projectile means in said projectile chamber, shoulder means projecting outwardly from the outer surface of said body member adapted to locate and support the cartridge in the gun, said wall means functioning as a piston against which the combustion gases act to expel said body member and said projectile means positioned therein as a unit through said gun barrel upon firing of said cartridge, the separation of the body member from the projectile means being accomplished after the body member and the projectile means leave the muzzle of the gun.

8. An expendable cartridge comprising: a tubular resilient plastic casing; an outwardly and rearwardly tapering shoulder formed on the outside surface of said casing intermediate the ends. thereof to provide shot start resistance for said cartridge in a firearm; a transverse web fixed to the interior of said casing intermediate the ends thereof to divide said casing into forwardly and rearwardly facing open-ended cups, said web sealing said forward cup from said rearward cup; projectile means positioned in said forwardly facing cup; and a propellant with an integral primer positioned in said rearwardly facing cup.

9, The cartridge of claim 8, wherein said forwardly facing cup has an outside diameter which is less than the outside diameter of said rearwardly facing cup and said shoulder is positioned between and interconnects both of said outside diameters of said cups.

10. The cartridge of claim 8, further comprising thinwalled frangible means closing a mouth of said forwardly facing cup.

11, The cartridge of claim 8, wherein said shoulder is interrupted by undercut portions operative to lower the shot start resistance provided by said shoulder.

12. The cartridge of claim 8, further comprising a forwardly extending flexible flange formed on said shoulder and operative to provide a readily deformable seating surface for said casing when chambered in a firearm.

13. The cartridge of claim 8, further comprising a relatively light weight cup overlying said projectile means to close a mouth of said forwardly facing cup, and a cone crimp formed on a rim of said forwardly facing cup and overlapping the edge of said light weight cup to hold the latter in place 4. The cartridge 0 claim 8, further comprising resilient means formed on said rearwardly facing cup and operative to overlap said propellant thereby retaining the latter in said rearwardly facing cup.

15. The cartridge of claim 8, further comprising resilient means formed on a mouth of said rearwardly facing cup and operative to releasably engage a firearm bolt thereby providing for extraction of an unfired car tridge.

v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTEON Patent No.3,728,966 Dated April '24, 1973 Inventor(s) William 'B. Woodring It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: In Col. 2, line 15, please delete "0s" and insert --is--; In Col. 2, line 16, please delete "is" and insert -mo di fied;

Signed and sealed this 26th day of March. 197L (SEAL) Attest:

EDWARD'M.FLETCHER,JR. Q. MARSHALL DANN Attest ing Officer Commissioner of Patents FORM PO-IOSO (10-69) -pc 5Q375.p5

- a U5. GOVERNMENT IRINTIG OFFICE Z 0-355-334 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION A, Patent No. 3,728,966 Dated April 24, 1973 Inventor(s) William B. Woodring It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: In Col. 2, line 15, please delete "0s" and insert --is-; In Col. 2, line 16, please delete "is" and insert --modified--;

Signed and sealed this 26th day of March 197L (SEAL) Attest:

EDv-IARD'M.FLETCHER,JR. MARSHALL DANN Attest ing Officer Commissioner of Patents FORM F G-1050 (1.0-69) uscoMM-Dc we're-P69 U.S. GOVERNMENT IRINTING OFFICE: I9! 0-366-384 

1. A cartridge casing of deformable plastic material which is completely expelled from the muzzle of a firearm when fired, said casing comprising: a tubular plastic body; a transverse web fixed to the interior of said body intermediate the ends thereof to divide said body into forward and rearward portions; and shoulder means formed on the exterior surface of said body to provide shot start resistance to said casing when chambered in a firearm, said shoulder means comprising circumferentially spaced shoulders separated from each other by undercut portions.
 2. A cartridge including an open ended tubular plastic casing, said casing having a forward portion of reduced diameter and a rearward portion of enlarged diameter, a shoulder between said forward and rearward portions, a transverse web positioned within said casing and forming a common wall between said forward and said rearward portions, wad means positioned within said forward portion, projectile means positioned within said forward portion, closure means closing an end of said forward portion, and propellant means positioned within said rearward portion of said casing.
 3. A firing system in which the entire cartridge is expelled from the muzzle of a firearm, said cartridge comprising a cartridge case and an associated projectile means, said cartridge case being made of deformable, plastic material and comprising an elongated, generally tubular member having a mouth end and a breech end at the opposite end thereof, transverse wall means integrally formed intermediate said ends to form with said elongated member an open-ended propellant cavity at the breech end and an open-ended projectile cavity at the mouth end, projectile means positioned and secured in said projectile cavity, said propellant cavity having its open end closed off by a molded, consumable propellant means which is substantially entirely consumed upon firing, consumable ignition means positioned and secured in said propellant means, said firearm from which said cartridge is to be expelled after firing comprising a gun barrel having a bore of lesser diameter than said cartridge case and a gun chamber in which said cartridge is positioned for firing, means abutting said cartridge to limit forward movement of the cartridge into the chamber prior to firing and to give support thereto during firing, said cartridge case adapted to be deformed so as to be entirely expelled through the smaller bore diameter of the gun barrel upon firing without leaving any portion thereof in the gun.
 4. An expendable cartridge comprising a case made of deformable plastic material which is not combustible under normal firing conditions, a transverse wall means integrally formed with said case to define an open-ended projectile chamber at its mouth end and an open-ended propellant chamber at its breech end, said cartridge case being of maximum diameter adjoining said propellant chamber and of minimum diameter adjoining said projectile chamber, projectile means at least partially positioned in said projectile chamber and secured therein, propellant means, at least a portion of which is of solid unitary construction, positioned in said propellant chamber so that said solid propellant portion closes off the open end of said propellant chamber, priming means positioned in and secured to said solid propellant portion, said propellant means and said priming means being entirely made of consumable materials so that Upon firing said propellant means and said priming means are substantially entirely consumed whereupon said plastic cartridge case is deformed and forced out of the gun barrel behind the projectile means thus resulting in the entire cartridge being expelled from the gun.
 5. A shotshell which is expelled from the gun upon firing comprising an expendable body having a rear chamber open at its rear end thereof, propellant means and priming means positioned and secured in said rear chamber, a forward chamber open at its front end and having a shot charge positioned therein, imperforate wall means separating said forward and rear chambers to prevent explosive gases formed in the rear chamber from entering said forward chamber, a shoulder means formed integrally with said body on the outer surface thereof between the open ends thereof, and closure means closing off the open end of said front chamber to confine the shot charge in the front chamber during handling but adapted to release the shot charge after the expendable body and shot charge are explosively expelled from the muzzle of the gun.
 6. An expendable shotshell cartridge comprising a thermoplastic body member having a first chamber open at one end, propellant means and priming means positioned and secured within said first chamber, a second chamber at the opposite end of said body member from the first chamber, a shot charge positioned in said second chamber, said first and second chambers being separated from each other by an imperforate wall means which remains attached to the body member after firing, a continuous rim means formed integrally with the body at the open end of said first chamber to act as a seal and to provide support to hold the shell in a gun chamber, said rim means being adapted to hinge inwardly under pressure upon firing of the cartridge and to remain attached to the body while the entire cartridge and shot charge therein is expelled from the muzzle of the gun.
 7. An expendable cartridge adapted to be expelled from the barrel of a gun, said expendable cartridge comprising a body member made of thermoplastic material, a transverse, imperforate wall means formed with said body member to define therewith a propellant chamber at the rear thereof and a projectile chamber at the front thereof, projectile means positioned in said projectile chamber, propellant means and priming means positioned in said propellant chamber, transverse closure means retaining said projectile means in said projectile chamber, shoulder means projecting outwardly from the outer surface of said body member adapted to locate and support the cartridge in the gun, said wall means functioning as a piston against which the combustion gases act to expel said body member and said projectile means positioned therein as a unit through said gun barrel upon firing of said cartridge, the separation of the body member from the projectile means being accomplished after the body member and the projectile means leave the muzzle of the gun.
 8. An expendable cartridge comprising: a tubular resilient plastic casing; an outwardly and rearwardly tapering shoulder formed on the outside surface of said casing intermediate the ends thereof to provide shot start resistance for said cartridge in a firearm; a transverse web fixed to the interior of said casing intermediate the ends thereof to divide said casing into forwardly and rearwardly facing open-ended cups, said web sealing said forward cup from said rearward cup; projectile means positioned in said forwardly facing cup; and a propellant with an integral primer positioned in said rearwardly facing cup.
 9. The cartridge of claim 8, wherein said forwardly facing cup has an outside diameter which is less than the outside diameter of said rearwardly facing cup and said shoulder is positioned between and interconnects both of said outside diameters of said cups.
 10. The cartridge of claim 8, further comprising thin-walled frangible means closing a mouth of said forwardly facing cuP.
 11. The cartridge of claim 8, wherein said shoulder is interrupted by undercut portions operative to lower the shot start resistance provided by said shoulder.
 12. The cartridge of claim 8, further comprising a forwardly extending flexible flange formed on said shoulder and operative to provide a readily deformable seating surface for said casing when chambered in a firearm.
 13. The cartridge of claim 8, further comprising a relatively light weight cup overlying said projectile means to close a mouth of said forwardly facing cup, and a cone crimp formed on a rim of said forwardly facing cup and overlapping the edge of said light weight cup to hold the latter in place.
 14. The cartridge of claim 8, further comprising resilient means formed on said rearwardly facing cup and operative to overlap said propellant thereby retaining the latter in said rearwardly facing cup.
 15. The cartridge of claim 8, further comprising resilient means formed on a mouth of said rearwardly facing cup and operative to releasably engage a firearm bolt thereby providing for extraction of an unfired cartridge. 